A blank cartridge of this type corresponds to the blank cartridges as they have been used for some one hundred years and are still used in many countries in weaponry.
In such a known blank cartridge the projectile of the live cartridge is replaced by a hollowed, slightly under-calibrated wooden projectile, which is supposed to be broken down into small splinters by the highly aggressive propellant charge powder, if possible still inside the barrel, such that these splinters cannot injure persons even shortly after leaving the muzzle.
Actually, in practice it has turned out, however, that a hazardous zone of 10 m in front of the muzzle must be taken into account.
Such a blank cartridge has the advantage that its spent casing corresponds in its dimensions exactly to the spent live cartridge; actually, the cartridge casings of live cartridges which have already been fired have been reused for blank cartridges.
However, a disadvantage is that due to the low projectile weight and gas pressure such blank cartridges cause no recoil or gas pressure which is necessary for the reloading of automatic weapons, while, on the other hand, the wood splinters generated during firing prevent the use of a training cartridge device which narrows the muzzle and thus dams up the propellant gases.
Now, on the one hand, it has been proposed to use a projectile jacket, filled with metal powder and which breaks down, as a training projectile (DE-AS 1 239 961), whose weight approximates that of the live projectile, but which, as a result of its pronounced-spin, is supposed to break down immediately after leaving the muzzle. An automatic loading weapon may be loaded with such a blank cartridge; however, there are significant safety reservations against the general use of a projectile of this design.
On the other hand, blank cartridges in which the casing bottom made of metal is fastened in a plastic casing on the front of which the hollow projectile is formed in one piece are used nowadays to a large extent; in the tip of the hollow projectile a predetermined breaking point is formed, which bursts open upon firing such that the resultant damming provides for the proper burning away of the charge which consists of a fast-burning powder similar to a shotgun powder.
The danger that, upon firing, parts of the plastic hollow projectile will fly off is certainly slight, however, it does exist and must thus not be overlooked, if no training cartridge device is used. With a training cartridge device attached, however, a weapon uses such blank cartridges largely safely and problem-free, as long as the plastic jackets of the blank cartridges do not melt in a hot cartridge chamber. A prerequisite for this is, however, that the spent blank cartridges cause no problem during ejection, since they are clearly longer that an empty cartridge casing of a live cartridge. Unfortunately, there is now a significant number of weapons which do not eject such blank cartridges without problems, such as automatic reloading weapons built into vehicles with a casing sack or a casing ejection channel.
During maneuvers, the shooters then learn the elimination of frequent loading obstacles which do not occur at all in live shooting, and, in the process, too easily lose confidence in the weapon.
Blank cartridges are also known in which a hollow cylinder is formed on the neck of the metal casing whose opening is flanged inward such that this hollow cylinder has the external shape of the projectile.
Upon firing, the hollow cylinder unfolds and remains on the casing such that on the whole the same problems result as with the above-described plastic blank cartridges.
And finally, with the firing of blank cartridges of absolutely all types, the oil or grease film which is intended to protect the barrel surface from corrosion, bums away, since a regreasing of the barrel by projectiles as has been known for centuries cannot occur. Multiday maneuvers in bad weather thus result in damage to the weapons used because experience has shown that the instruction to shooters to swab the barrels from time to time is not followed.
There is a particular problem when blank cartridges of the type described are to be used in filmmaking, in particular along with a training cartridge device: There, because of lighting a more pronounced muzzle flash is required than is adequate and appropriate for military training purposes.
It is not possible simply to increase the amount of the propellant charge since because of the very rapidly burning powder, this is already somewhat critical.
On the other hand, it is not simply possible to add magnesium powder or a similar illuminant to the propellant charge, since the burning behavior of the propellant charge may be drastically altered by this. Also, pieces of the illuminant, which burns at an extremely high temperature are sprayed into the surface of the inside wall of the barrel, where they may cause or trigger damage.
And finally, it must be taken into account that particularly high demands must be placed on the safety of blank cartridges which are to be used in filmmaking or the like since when he fires, the respective actor is not concentrating primarily on the handling of the weapon, as does a soldier in maneuvers, but rather on the portrayal of the character he is playing.
In EP 00 44 643 A1, it has been proposed to use a projectile made of polyurethane for a blank cartridge, which is supposed to be completely consumed while still in the barrel of the weapon, whereby it is assumed that the particles of the polyurethane projectile shattered by the firing acceleration come into contact with the excess oxygen of the propellant gases and thus possibly burn up; however, it is more likely that at least part of these particles might leave the muzzle without having burned. Thus, with these prior art blank cartridges, safety reservations persist.
The technical manual of weaponry "Rheinmetall", 7th ed. 1985, pages 465 and 518, shows the blank rifle cartridge ("training ammunition") used by the German Bundeswehr made of a closed-front plastic casing provided with a predetermined breaking point in the form of a cartridge on the back end of which a metal bottom with an igniter is inserted. When fired, the casing bursts. The spent cartridge is not intended to be reloaded.
DE 70 16 258 U1 presents a blank cartridge which works on the same principle: However, the plastic casing which has a predetermined breaking point on its front end is designed not in the shape of a complete cartridge, but rather only as a projectile; this projectile-shaped plastic casing sits solidly in the cartridge casing, for example, in the center of a flange.
Utility model DE 16 99 603 presents a blank or gas cartridge which was commercially available in the 1950s under the tradename "Wadie" and had a so-called "blank charge" of loose powdered material over a propellant charge, which can, for example, consist of coarse grain (as a blank cartridge), perfume-soaked asbestos powder (as a perfume cartridge), flash powder, or a mixture of black powder and flash powder (as a flash powder cartridge) or soot (as a smoke cartridge). The burning of the powdered "blank charge" serves in this case merely for effect. To intensify this effect, if possible, burning outside the muzzle must be sought. Actually, the effect occurs in cartridges with low thermal energy and low firing pressure--as in the Wadie cartridges--that a relatively large proportion of propellant powder is ejected unconsumed from the barrel. Now, if one loads a flash charge as a projectile, so to speak, before the propellant charge, then it is to be expected that the greater part of it will not ignite, but is simply ejected from the muzzle. Of the possibilities mentioned in the published utility model, only the blank cartridge, the gas cartridge, and the perfume cartridges of "Wadie" are known; to our knowledge a flash cartridge was never produced. On the whole, this cartridge is known only as a curiosity.
DE 38 15 436 A1 concerns a molded propellant charge made of powder grains and binder for artillery cartridges. Molded propellant charges are also known in casingless small arms cartridges. In each case the propellant charge (but not the projectile) is laced with binder. If one wished to implement the teaching of this published patent in a blank cartridge, the "blank charge" would, however, have to remain in powder form in order to avoid obstructions in the weapon resulting in a dangerous increase in pressure which would prevent the firing of projectiles.
DE 30 08 144 A1 concerns "combustible molded pieces of ammunition" made of felt. This means hollow molded forms of felt to accommodate a propellant charge for the artillery. The purpose of these molded forms of felt is to burn out during and after firing so that the next loading procedure is not blocked by old charge residues.
Patent GB 924 390 concerns an artillery training cartridge (caliber greater than 40 mm) with a reusable outer casing, in which a projectile-shaped plastic body and a type of inner blank cartridge are removably fastened, possibly screwed in. The body has predetermined break points and operates in principle like the aforementioned Bundeswehr training cartridge. The inner blank cartridge is screwed from the front into a central continuous open neck formed in the base and has an igniter, which connects flush with the base after incorporation of the inner blank cartridge. After firing of the training cartridge, the residues of the projectile-shaped body and the spent inner blank cartridge are removed and replaced by a new body and a new blank cartridge, respectively. It also concerns creating an exchangeable blank cartridge load, the diameter of which is small enough that it passes through the neck of the cartridge.
U.S. Pat. No. 1,804,986 concerns a blank cartridge which consists of a relatively small caliber standard blank cartridge and an adapter for the weapon actually used. The adapters may be produced as turned parts, collected after firing, and reloaded with a new blank cartridge. Thus it is possible to produce a large number of different types of cartridges simply and inexpensively.